Speed control device for a model airplane engine



Sept. 8, 1970 L. K. JENNINGS SPEED CONTROL DEVICE FOR A MODEL AIRPLANEENGINE 2 sheets sheet l Filed Feb. 17, 1969 INVENTOR. LUTHER K. JENNINGSATTORNEY.

' Se t. 8, 1970 L. K. JENNINGS 3,527,255

SPEED CONTROL DEVICE FOR A MODEL AIRPLANE ENGINE 2 Shec ts-Shee t 2Filed Feb. 1'7, 1969 INVENTOR.

ATTORNEY.

United States Patent 3,527,265 SPEED CONTROL DEVICE FOR A MODEL AIRPLANEENGINE Luther K. Jennings, 2712 Summerfield Road, Winter Park, Fla.32789 Filed Feb. 17, 1969, Ser. No. 799,661 Int. Cl. F02d 9/06, 33/ 00;F02m 25/06 US. Cl. l2398 Claims ABSTRACT OF THE DISCLOSURE Thecarburetor air inlet of a model airplane engine is provided withrelatively shiftable inner and outer sleeves for selectively effectingcommunication of the air inlet with the ambient air and the engineexhaust.

BACKGROUND OF THE INVENTION While speed control devices for internalcombustion engines are not new, and have assumed many forms, there hasnot been provided in the past any satisfactory speed control mechanismfor relatively small internal combustion engines of the type employed inmodel airplanes. Hence, it has been customary in the past to operatemodel airplane engines at full throttle without varying the enginespeed.

SUMMARY OF THE INVENTION Accordingly, it is an important object of thepresent invention to provide a speed control device for use with modelairplane engines which can accurately vary the en gine speed betweenfull throttle and an idle speed.

It is a further object of the present invention to provide a speedcontrol apparatus of the type described which is extremely simple inconstruction, requiring a minimum of parts, and conveniently operable bythe user.

It is still a further object of the present invention to provide a speedcontrol device for model airplane engines, having the advantageouscharacteristics mentioned in the preceding paragraphs, which is staunchand durable in construction for reliable operation throughout a longuseful life, can be readily incorporated with conventional modelairplane engines, either as original equipment or as an attachment, andwhich can be economically manufactured for sale at a reasonable price.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawings,which form a material part of this disclosure.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, which will beexemplified in the construction hereinafter described, and of which thescope will be indicated by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational viewshowing a model airplane engine employed in conjunctionwith a speedcontrol device in accordance with the teachings of the presentinvention.

FIG. 2 is a top plan view of the assembly of FIG. 1.

FIG. 3 is an exploded perspective view showing the speed controlmechanism of the present invention apart from the remainder of theengine.

FIG. 4 is a partial horizontal sectional view taken generally along theline 44 of FIG. 1, illustrating a full speed operational position of thespeed control mechanlsm.

FIG. 5 is a horizontal sectional view similar to FIG. 4, butillustrating an idle speed position of the control mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularlyto the drawings, and specifically to FIGS. 1 and 2 thereof, a modelairplane engine is there generally designated 10, which may be a singlecylinder engine including a cylinder block 11 provided on its upper endwith a cylinder head 12, and on its lower end with a crank case 13. Acylinder exhaust extends laterally from one side of the cylinder block,as at 15, and a drive shaft 16 extends from one end of the crank case13. The engine block 11 may be provided with lateral wings 17 formounting the engine on a suitable bed.

Upstanding from the crank case 13 is a carburetor generally designated20. The carburetor may include a generally cylindrical body 21 havingits lower end connected for fluid communication with the interior of thecylinder block 11 in any suitable manner. The upper end of thecarburetor body 21, as at 22, may provide an air inlet for thecarburetor. A fuel conduit 23 may be connected at one end to a fuelsupply (not shown), and connected at its other end by a fitting 24, tothe interior of the carburetor body 21 for delivering fuel thereto. Aneedle valve 25 may be mounted in the carburetor body 21 opposite thefuel inlet fitting 24 for varying the opening thereof. That is, theneedle valve 25 may be rotated by its handle 26 in opposite directionsto regulate the fuel flow to the carburetor. To maintain the needlevalve 25 at a selected position of its rotative movement, as for passinga desired rate of fuel to the carburetor, the needle valve may beprovided with a toothed or serrated wheel 27 for rotation with theneedle valve, and one or more resilient or spring fingers 28 fixed atone end to the carburetor body and in frictional bearing engagement withthe wheel 27. In this manner, the needle valve 25 is effectively held atany selected position of adjustment even under severe conditions ofvibration and other motion. Of course, the needle valve 25 may serve toregulate the fuel supply and the resultant engine speed, but this modeof speed regulation is extremely limited and inconvenient.

Mounted on the body 21 of carburetor 20, particularly on the air inletend 22 of the carburetor body, is the speed control device of thepresent invention, there generally designated 30. As best seen in FIG.3, the speed control mechanism includes an inner sleeve 31 defined by anopen ended generally cylindrical tube, which may have its lower end 32fixedly secured to the upper end of the carburetor body 21 for fluidcommunication with the air inlet of the carburetor. Formed in the innersleeve or tube 31 is an elongate opening or slot 33. It will be observedthat the elongate opening or slot 33 extends partially circumferentiallyabout the tube 31, approximately one-half the circumference thereof, andis spaced between the lower tube end 32 and the upper tube end 34. Asbest seen in FIGS. 4 and 5, the inner sleeve or tube 31 is fixedlysecured in end-to-end aligned relation with the upper or air inlet endof the carburetor body 21, the elongate opening or slot 33 facingobliquely forwardly and laterally to the right, as shown in theillustrated embodiment.

Rotatably circumposed about the inner sleeve or tube 31, in snug slidingrelation therewith, is an outer sleeve or tube 35. That is, the outersleeve 35 is defined by an open ended tube rotatably surrounding theinner sleeve or tube 31 and approximately longitudinally coextensivetherewith. Formed in the outer sleeve or tube 35 is a through hole 36,which is spaced intermediate the lower and upper tube ends 37 and 38 soas to lie in facing relation with the inner sleeve opening or slot 33.That is, the outer sleeve or tube 35 is rotatable coaxially with theinner sleeve or tube 31; and, the generally circular outer sleeveopening ir hole 36 is movable with the outer sleeve between a forwardlocation, as in FIG. 4, in alignment or registry with a forward endregion of the slot 33, and a sideward location in alignment or registrywith a sidewardly facing region of the slot 33, as in FIG. 5. Ifdesired, suita'ble stop means may be provided to limit rotation of theouter sleeve 31 between the extreme positions shown in FIGS. 4 and 5. Ofcourse, the outer sleeve 31 may be placed in any selected position ofrotation intermediate the extreme illustrated positions, as desired.

The upper ends of the inner and outer sleeve 31 and 35 are effectivelyclosed by suitable closure means, such as a plug 40 engageable in theupper end of the inner sleeve. The plug or closure means 40 thus closesthe upper ends of the coaxial sleeves 31 and 35, and, by its up wardlyenlarged configuration effectively retains the outer sleeve in positionon the inner sleeve. An operating member or arm 41 may be fixed to theouter sleeve 35, extending generally tangentially therefrom, for remoteactuation of the outer sleeve to selectively position the latter in anydesired relation with respect to the inner sleeve. Suitable remoteactuating means may be connected to the operating arm 41, if desired.

A by-pass conduit is generally designated 43, and includes anintermediate tubular portion 44 having one side open, as at 45 for fixedsecurement in communicating relation with the cylinder exhaust 15.Extending from one end of the intermediate by-pass conduit portion 44 isa conduit portion 46 which terminates in an open end 47 proximate to andfacing toward the outer sleeve 35. Further, the by-pass conduit end 47is advantageously configured for conforming facing relation with thecylindrical exterior surface of sleeve 35 and located in alignment withthe laterally facing portion of slot 33. Extending from the other end ofthe intermediate 'by-pass conduit portion 44 is an outlet portion ortailpipe 4 8. Thus, the engine exhaust communicates through the sideopening 45 of the by-pass conduit 43 both with the conduit 46 extendingto the exterior of outer sleeve 35, and through the tailpipe portion 48with the ambient atmosphere.

It will now be appreciated that the conformably configured end 47 ofby-pass conduit 43 is in conforming facing relation with the exteriorsurface of outer sleeve 35, and that the latter is rotatable toselectively place the hole or aperture 36 in aligned registry with theconduit portion 44, as in FIG. 5, and out of alignment therewith, as inFIG. 4. The outer sleeve 35 is thus interposed between the inner sleeve31 and the conduit end 47, and may be slidable therebetween.

In the condition of adjustment of outer sleeve 35 as shown in FIG. 4, itwill be apparent that the hole 36 of the outer sleeve communicatesbetween the forward region of slot 33 of inner sleeve 31 and theexterior atmosphere or fresh air. Thus, a maximum quantity of air andoxygen may be drawn into the inner sleeve 31 and to the carburetor airinlet 22 for high entrance speed. In this condition, the by-pass conduit43 is closed by the outer sleeve 35 across conduit end 47, so thatexhaust gases proceed as indicated by the arrows 50, all exiting throughthe tailpipe 48.

In the condition of adjustment of outer sleeve 35 as shown in FIG. 5,the hole or aperture 36 is in alignment or registry with the by-passconduit end 47, so that the by-pass conduit communicates through thehole 36 and slot 33 with the interior of inner sleeve 31 to the airinlet of the carburetor 20. In this condition a minimum of fresh air andoxygen may be drawn into the air inlet of the carburetor, although theremay be successful operation with appreciable leakage. However, asubstantial proportion of exhaust gases from exhaust outlet 15 pass inthe direction of arrows 51 through by-pass conduit portion 46 and enterthrough hole 35 and slot 33 to the interior of inner sleeve 31, forpassage to the carburetor 20. As this mixture of gases to the carburetorcontains less oxygen, the engine speed is considerably reduced, as to anidling speed. Of course, intermediate positions of the outer sleeve 35,as with the hole 36 partially communicating with both the by-passconduit portion 46 and the fresh or ambient air may be employed toobtain speeds intermediate those of idling and full throttle.

From the foregoing, it is seen that the present invention provides aspeed control device for a model airplane engine which fullyaccomplishes its intended objects and is well adapted to meet practicalconditions of manufacture and use.

Although the present invention has been described in some detail by wayof illustration and example for purposes of clarity of understanding, itis understood that certain changes and modifications may be made withinthe spirit of the invention.

What is claimed is:

1. A speed control device for a model "airplane engine having a cylinderexhaust and carburetor air inlet, said device comprising an inner sleevehaving one end connected in fluid communication with said air inlet,said inner sleeve having a through slot communicating between theinterior and exterior of said inner sleeve, an outer sleeve slidablyengaged over said inner sleeve in covering relation with said slot, saidouter sleeve having a through hole movable with said outer sleeve andcommunicating through said slot at spaced locations thereof uponmovement of said outer sleeve, and a by-pass conduit communicatingbetween said exhaust and the exterior of said outer sleeve adjacent toone of said locations, whereby outer sleeve movement to position saidhole at said one location eflects communication of said exhaust withsaid air inlet for reducing engine speed and outer sleeve movement toposition said hole at another location effects communication of freshair with said air inlet for increased engine speed.

2. A speed control device according to claim 1, said inner sleevecomprising a cylindrical tube, said slot being partially circumferentialin extent, and outer sleeve comprising a cylindrical tube rotatablycircumposed about said inner sleeve tube, said hole being located insaid outer sleeve tube for rotative movement therewith between said onelocation communicating with said by-pass conduit and said other locationcommunicating with ambient air.

3. A speed control device according to claim 2, in combination withclosure means closing said inner and outer sleeve tubes remote from saidair inlet.

4. A speed control device according to claim 3, said bypass conduithaving one end configured for conformance with said outer sleeve tube.

5. A speed control device according to claim 3, in combination with anoperating arm connected to said outer sleeve tube for selectivepositioning of the latter.

References Cited UNITED STATES PATENTS 1,380,173 5/1921 Abel 123-1l91,552,819 9/1925 Brush et al. 123119 2,627,851 2/1953 Cushman 123 107 XR 2,030,508 2/ 1936 Falconer 123-119 2,806,458 9/1957 Mett et a1 12398XR 2,921,568 1/1960 Mett et a1 123-107 2,940,434- 6/1960 Stanzel 123-107WENDELL E. BURNS, Primary Examiner US. Cl. XJR. 123107, 119

